Although rare, HFMD can spreads in pools due to poor bathroom hygiene

There are more than 200,000 cases of HFMD annually, and there's no cure

The highly contagious disease is caused by several viruses and it primarily affects little kids. It causes red spots in and around the mouth, hands, feet, and even the buttocks. They often become painful water-filled blisters that can burst and cause small ulcers. Eating and drinking is uncomfortable for about a week so patients need to be careful not to become dehydrated.

Adults usually have some immunity to HFM Disease—but can still spread it

In 2025, certain eastern states including Virginia and West Virginia reported a sizable uptick in their HFMD cases, particularly in their schools and daycare centers, though the reason for the larger outbreaks remains unknown. When adults or teens get the disease, their symptoms are usually mild or even asymptomatic. Still, they may pass the disease between people, too. (Some users may encounter a paywall.)

Hand, foot, and mouth disease spreads easily—including via fomites

The common ailment spreads through respiratory droplets, touching infected secretions like poop, but also by touching virus-laden fomites, which are contaminated objects such as doorknobs or toys.

We can get food poisoning from spending time in swimming pools, lakes, rivers, and ponds

Some of the same pathogens that may sicken us in food or water may also sicken us in recreational swimming environments. Bacteria can rub off of people’s (or animal’s) bodies or contaminate the water through a diarrheal episode. Washing your hands for at least 20 seconds before eating food if you are at the beach, pool, or other similar environments and being sure not to swallow the water are ways to help keep safe.

In 2012, a virus that causes HFMD may have killed dozens of kids in Asia

More than 50 young children in Cambodia died in spring 2012 for unknown reasons, but laboratory testing of samples available from a limited number of those children came back positive for Enterovirus 71. That virus, which can cause HFMD, is known to cause severe complications among some people who contract the disease. But health officials concluded that poor baseline health and then incorrect treatment using steroids helped exacerbate their condition, helping lead to the deaths.

Polio commonly spreads when virus-laden feces gets into our mouths

This highly infectious disease is transmitted from one person to another, mainly when we eat virus-laden poop particles. Less frequently, contaminated food or water can transmit the virus, or people can be infected via respiratory droplets (from coughing or sneezing).

HFMD can survive on surfaces for days at a time

That's why the virus can be transmitted via fomites—surfaces that have virus on them like doorknobs, kids toys, etc. These viruses are resilient—they are often even resistant to freezing (and are frequently stored at freezing temperatures in lab settings).

CDC does not require docs to report hand, foot, and mouth cases which makes tracking difficult

Mid-Atlantic states saw a surge of hand, foot, and mouth disease in 2025 for as-yet unknown reasons. Virginia, Maryland, and New Jersey, reported elevated outbreak numbers in 2025 as compared to other recent years, but since the US Centers for Disease Control and Prevention does not require mandatory reporting of positive HFMD cases—unlike strictly notifiable diseases like measles—it's hard to truly know the extent of the outbreaks and how significant the caseload is as compared to prior years across the region or country.

HFMD was first reported in 1957 in New Zealand

The first clinical report involved eight kids with the characteristic sores in New Zealand, and then in the years that followed there were dozens more cases there and also reports of outbreaks in England and Scotland, among other settings, including the US.

HFMD symptoms typically begin to show up 3-6 days after exposure

Fever is often the first symptom and then painful sores may develop a day or two later. Coxsackie A16 is currently the most common enterovirus that leads to the disease, though there are several other enteroviruses that can cause it as well.

Swimmer's ear is America's most common waterborne illness

Federal government analysis of the roughly 7 million waterborne illness cases that occur annually in the US found that swimmer's ear comprises some 4.7 million, or 65%, of the annual waterborne illnesses and 20% of hospitalizations. Norovirus infection comes in second place.

About 20% of people infected with cholera have severe symptoms

That's according to studies from outbreaks in Bangladesh. Most people who contract the disease have mild or moderate symptoms, or none at all. Yet anyone infected with the disease-causing bacteria can shed the pathogens in their feces for a few days, or even up to around 10, seeding the environment with bacteria.

Watch an expert's take on the rare disease hantavirus—and why it's not of great concern to the general population

This rare zoonotic disease, transmitted to humans primarily through infected rodent droppings, urine, or saliva, is rarely spread between people. The disease was of particular concern in spring 2026, when an outbreak occurred on a 150-person cruise ship, prompting a flurry of action, including contact tracing for passengers in their home countries. The disease can be fatal. But early care—primarily oxygen support—can help patients survive.

Human-to-human transmission of hantavirus remains extremely rare, so the 2026 hantavirus cruise ship outbreak doesn't mean we're facing a COVID-style pandemic risk.

Horses can—rarely—get West Nile, too

The animals can contract the virus via infected mosquito bites, but for horses there are four vaccines available. Though West Nile's often asymptomatic or mild in horses, the disease can sometimes be deadly, killing via severe neurological inflammation. There are no reported instances of people becoming sickened by infected horses or vice-versa.

Cryptococcus neoformans, a growing threat, causes infections in the brain and lungs

This inhalable, microscopic pathogen is found worldwide. It rarely causes illness, but it can take root in those with compromised immune systems, including people with advanced HIV/AIDS. Symptoms of cryptococcal infection—such as a stiff neck, vomiting, and confusion—can begin weeks or months after breathing in spores, though sometimes symptoms won’t appear for years. There are no known cases of transmission between people or between people and animals.

What happens when the gut microbiome is out of whack?

An imbalance in gut microbiome flora can lead to a condition known as dysbiosis. This condition is typically characterized by a drop in microbiota diversity and an increase in harmful unicellular and acellular organisms, such as viruses, that can negatively impact the host's immune system and overall health. Genetics, infections, dietary choices, antibiotics, food additives, artificial sweeteners, and other lifestyle and environmental factors can cause dysbiosis.

Measles attacks the body’s immune system, leaving it vulnerable to secondary complications

A measles infection begins in the lungs, where it hijacks cells known as macrophages and begins to replicate itself. It then uses a Trojan horse method to enter the lymph nodes, where it attacks vulnerable T and B cells. Symptoms include fever and rashes.

How fecal transplants work

1,700 years ago, Chinese alchemist Ge Hong was renowned for his soup that could cure diarrhea-stricken patients. It had a surprising secret ingredient: feces. While it might seem unwise to consume feces, exciting new research suggests that taking...

See this graphic of the complex malaria transmission lifecycle

Female Anopheles mosquitoes contract malaria by feeding on the blood of a human already infected with the disease-causing parasite. The parasite then develops in the mosquito's gut for one to two weeks before it migrates to the mosquito's salivary glands. Next, when the mosquito bites another person the parasite is delivered into the bloodstream of another human. This graphic further details what happens inside the human body during infection.

Neglected tropical diseases affect more people than the population of Europe

This group of conditions, which includes hookworm, sickens roughly one in seven people on the planet—a tally which dwarfs Europe's population of roughly 450 million. International cooperation and donations are helping to control some of these illnesses, which can be caused by parasites, viruses, and bacteria. They're all treatable or preventable, but primarily occur among poor, isolated communities that may not receive adequate care.

About 95% of people are naturally immune to leprosy

Contracting it requires prolonged contact with someone with the disease, meaning you'd have to be living with them. You cannot get leprosy from hugging someone with leprosy or sitting next to them. It's not known to pass from mother to fetus. The risk of transmission from armadillos is also likely low, but people should avoid touching wild animals for general safety.

Embracing poor hygiene in early life won't stave off allergies

The hygiene hypothesis, first proposed in 1989 by British immunologist David Strachan, suggests that early life exposure to microbes—like those from farm dust or pets—properly trains our immune systems to respond to threats. But sometimes the idea is misinterpreted: It doesn’t mean that poor hygiene—like failing to wash hands–will help ward off allergies; that type of behavior leads to infections and won’t help with allergy prevention.

Climate change is influencing the spread of disease

Rising temperatures and water levels are forcing animals and pathogens beyond their typical boundaries. This article and its data visualizations explore the proliferation of climate-driven diseases.

Microplastics are entering human food chains through fertilized farmland

Microplastics from sewage sludge used as fertilizer contaminate agricultural soil and eventually enter our bodies through the food supply of carrots, wheat, and other foodstuffs. In Europe, farmland may absorb up to 710 trillion microplastic particles yearly.

Oral rehydration solution was developed in the 1960s in response to cholera deaths

Drinking this life-saving mix, which consists of clean water, salts, and sugar, helps the human body rehydrate after extreme bouts of diarrhea, vomiting, or both. It's now used for a variety of diarrheal diseases.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

Between 10 million and 50 million people in the US develop rashes from poison ivy, poison sumac, and poison oak each year.

See images of medical cases of firework injuries shared on this 'Instagram for doctors.' (Warning: Graphic content)

When caught in the mouths of cardinal fish, seed shrimp release glowing, bioluminescent chemicals, which alert predators of the cardinal fish, prompting the shrimp's ejection.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

Planarian flatworms are small, aquatic worms with exceptional regenerative capabilities. When cut, the worms can regenerate multiple bodies in a matter of weeks.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

Fast-casual restaurant Chili's is experiencing a resurgence, with its parent company recently reporting a nearly 32% increase in sales, thanks to passionate Gen Z fans on TikTok.

Hedge funds, the private investment firms that trade a wide swath of financial assets, make money by imposing steep fees on investors and from the fund's investment performance.

The United States is one of only around two dozen countries with a fully federal system of government, in which power is divided between national and state governments.

Double world record holder Hunter Ewen helped conquer his fear of balloons, called globophobia, by training to win Guinness World Record titles for balloon inflation.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

The US first hosted the World Cup in 1994, a tournament that lives in soccer infamy for its poor planning and the murder of Colombian player Andres Escobar, who'd accidentally scored on his own net.

The original copy of the Declaration of Independence is not a pristine document, and even features a smudged anonymous handprint in the bottom left corner.

Mid-century modern graphic designers, known for their bright colors and bold lines in advertising, also found success with children's books.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

'Saturday Night Fever,' the 1977 film that introduced disco to the mainstream, was based on a fabricated magazine story.